With respect to the grade, 10B38, it's a plain carbon steel that has been boron treated. A very good database that I've used for years when I didn't have in-house information available was
http://www.matweb.com/. You could find the composition and typical properties for the grade from this site. Since this is a heat treated grade, the properties depend upon your specification. As far as steel sources, if you are looking for bar products, try Republic Steel;
http://www.republicsteel.com/. Depending upon the bar size and order size, they would be able to produce the grade, but you'd need to inquire your specific order requirements. Again for bars, outside of Republic Steel, any of the major US bars manufactures should be capable of producing this grade. Timken, Charter or Gerdau would be other possible sources. If you're looking for sheet, strip or plate, I'd start with USS;
http://www.ussteel.com/. I've been away from that side of the business for too many years to offer other recommendations.
Bob